In the recent past, wearable “smart” devices became commercially available for a multitude of applications. Some of these applications require data on the current location of the device and its user. Accordingly, wearable devices are available that include a GPS module for satellite location detection. Other wearable devices allow to track the distance travelled, e.g., using an accelerometer sensor, but not the exact location of the device and its user.
Both of the aforesaid options provide disadvantages. Determining the distance travelled in most instances does not allow determining the user's location, even when combined with Wi-Fi or cellular assisted positioning, at least not to a typically desired accuracy. Using a GPS module instead certainly provides data of the user's location, which may be sufficient for many applications. However, GPS receivers typically have a high power consumption when switched on, which requires frequent recharging, in particular considering the typically small form factor of a wearable device and the accordingly limited battery capacity. Furthermore, it is known that determining the location using GPS takes a relatively long time for the necessary signal acquisition and analysis, which is why so-called “assisted GPS” modules were developed, using Wi-Fi or cellular signals to speed up the location determination. These modules however increase the power consumption even further. At last, a major drawback of GPS positioning is that, due to the frequency of the satellite GPS signals and the low transmission power density, determining a location using GPS is typically not possible indoors or in areas with poor satellite reception.
Accordingly, an object exists to provide an improved system for determining a location of a user, in particular for indoor use.